1. Field of Invention
The present invention relates generally to access control apparatus and, more particularly, to access control apparatus which are connected to remote locations by a telephone system.
2. Description of the Related Art
Apartment buildings, office buildings, condominium complexes, gated residential communities, industrial parks and other secured locations often include a locked entrance and a security system for establishing communication between visitors who wish to enter the secured location and persons who are capable of unlocking the entrance from a remote location. One type of security system uses existing telephone systems to establish such communication. In such a system, an access control apparatus, or call box, is provided at the entrance. The call box, which includes a keypad and an auto-dialer, is connected to a telephone line and to the entrance lock. A numbered directory of persons, businesses or other parties capable of unlocking the entrance is provided by the call box itself or on a sign located adjacent to the call box. When the visitor enters a code number into the call box keypad, the call box automatically dials the telephone number corresponding to the code number. Once the identity of the person who wishes to gain access is established, the called party can unlock the entrance by pressing a predetermined number into the keypad of the called telephone.
Prior access control apparatus, such as that disclosed in U.S. Pat. No. 5,027,111 to Davis et al., consist of a rigid metallic case having various electronic elements permanently housed therein. Access to the interior of the case is provided by a door. The electronic elements typically consist of a printed circuit board that includes a microprocessor, an EEPROM-type permanent memory, a volatile memory, a modem and a bus. Various input and output ports are also provided. These ports allow the electronic elements to be connected to telephone lines, computers, keyboards and handheld programmers. Necessary data, such as code numbers, telephone numbers and names, may be entered into the permanent memory from a remote location via the telephone line and modem, or locally through the use of a computer keyboard or handheld programmer that is plugged into one of the ports. The exterior of the box includes the aforementioned keypad as well as a speaker and a microphone. The speaker and microphone may be provided in the form of a telephone handset or mounted directly onto the metallic box. The keypad, microphone and speaker are connected to the printed circuit board by ribbon cables and other wiring.
Although generally useful for regulating entry into a secured location, there are a number of disadvantages associated with existing access control apparatus. The primary disadvantage is associated with programming the electronic elements and entering information into the permanent memory. Programming and data entry via a modem has proven to be quite complicated. In addition, existing modem based systems are difficult to use. The use of keyboards and handheld programmers is also problematic because the technician must stand next to the access control apparatus while entering data. As the vast majority of these units are located outdoors, technicians are often subjected the extreme heat in the summer and cold in the winter. Rain and snow present additional difficulties. It is also uncomfortable for the technician to stand next to the unit being serviced, hold a keyboard or handheld programmer with one hand, and type with the other.
Other shortcomings are associated with repair and maintenance. The metallic cases are often damaged or destroyed by vandals and thieves. In addition to being susceptible to this type of damage, the electronic elements are also prone to damage from extreme temperatures and power surges. The microphones are often damaged by moisture from rain or fog. The visual displays which are provided on the exterior of some existing call boxes are also easy targets for vandals. Existing keypads, which typically consist of a key and membrane switch arrangement that is mounted on the door of the metallic case, are also easily damaged when struck with a heavy object such as a baseball bat. Repairing a prior access control apparatus is a very expensive proposition. Because the speaker, microphone and printed circuit board containing the electronic elements are permanently mounted within the metallic case, it is difficult to remove them for repair or for substitution into a new case when the existing case is damaged. Also, if the memory fails, all of the data concerning names, code numbers, and telephone numbers will have to be re-entered, usually by hand by a technician forced to stand next to the unit.
Accordingly, a need exists for an access control apparatus that is easier to maintain, less susceptible to damage, and easier to repair than existing apparatus.
Other disadvantages associated with existing access control apparatus come into play when a visitor contacts, or attempts to contact, a party who is capable of unlocking a locked entrance. Existing access control apparatus include written instructions which explain how to find the name of the desired party on the directory list, select the associated code number, and cause the autodialler to make telephone or other electronic contact with the desired party. The level of detail of the instructions depends on the complexity of the access control apparatus. For example, those with electronic displays may include instructions explaining how to page through the list of names. Unfortunately, many people who are capable of picking a particular name out of a directory have difficulty reading instructions, either because of a language barrier or because of an inability to read. Persons who are visually impaired are also unable to read the written instructions and, therefore, are unable to use existing access control apparatus unless they are instructed in advance as to the code number associated with the party that they are visiting.
For visitors who are hearing impaired, existing access control devices are difficult to use because much of the process relies on audible communication. Once the visitor dials the code, a ringing signal is transmitted by a speaker, the ringing signal stops when the phone has been answered, the called party audibly indicates when he or she has answered the phone, and a buzzer is typically used to indicate that the door or gate has been unlocked. Thus, although hearing impaired visitors may be able to make contact with the party capable of unlocking the entrance and verbally identifying themselves into the microphone, they will not know when to do so and, once they have identified themselves, when the door or gate has been unlocked.
Accordingly, a need also exists for an access control apparatus which may be easily used by persons who have difficulty with written instructions, or who have hearing or sight related disabilities.
Once a visitor makes contact with the desired party through an existing access control apparatus, communication therebetween is often difficult because of echo which severely diminishes communication quality. Echo may be caused at the access control apparatus by feedback from the speaker to the microphone in a hands-free system or by prolonged background noise, either at the access control apparatus or at the called telephone. Echo can also be caused by electric signal reflection which is the result of impedance mismatches between a local two-wire loop and a four-wire telephone network. Thus, there is also a need for an access control apparatus having an echo cancellation system which eliminates echo generated at the apparatus, at the called party's location or by impedance mismatches.